Quaternary salts in mixed grain photographic emulsions



Patented Mar. 23, 1954 -.QUATERNAR.Y

SALTS IN iEMIXED ,PHOTOGRAPHIC EMULSIONS Burt H. Carroll, Rochester, N.Y., assignor to iEastman:.:Kodak Company, Rochester, N. Y., a

:cornorationzof NemJersey "N01 Drawing: Application October "Serial No.251383 (UL .v95-q2) fiiclaims.

'Ihisdnventiofihas to"dowith'photography and particularly to thesensitizing of mixed -grain emulsions.

'Ihesensitization of emulsions has-been described in carroll andiHan- Asensitizer diffusion. However, aimision is :seldom :completelyeliminated and difficulties halide grains varies with the silver halideused. In general, affinity is less for silver chloride than for silverbromide, so that there is the most difiiculty when itiis necessary toaavoid diffusion of 'Thisisituation is three-color-emul- :sion "where,it 1 is :desirable to use high chloride .aemu'lsions IfOI;th8red1sensitiveandrgreemsensr tive grains so1thatt.theirr;bluesensitivitywill :be negligible compared1to the blue-sensitive grains, orso that it canbe eliminated a yellow printing filter.

It is, therefore, an object of the present invention to provide a novelmethod of sensitizing .mixedngrain photosraphic-emulsions. A further.Qbjectis t'o provide a method for; preventing ssensitizer. diffusioniinmixed grain emulsions. A still further object is torprovidenovel mixedgrain gphotographicproducts. 'Other objects will .ap- .pear .from the,following 1 description 1 of any in- ,vention.

These objects are accomplished quaternary salts on the surface of-thesilver halide grainsof a mixed, grain photographic emulsion.

My invention comprises in general the provision of a mixed grainphotographicemulsion having to different spectral regions, in .a.hydrophylic carrier, one. .or. more of .the sets .of. grains; havinga...quaternary.salt.adsorbedthereto.

L'Ihe. silver'halide may ,be. silver chloride, silver .bromide, .silverchlorobromide, silver bromoio- ,;dide,..etc., .in..a..carrierv such..asgelatin, polyvinyl valcohol, hydrolyzed cellulose esters or ethers,etc.

The quaternary salts which .I .may use are quaternary salts ofcompounds=having the formula:

entirely by use of g by adsorbing of'the sensitizing dye for the silver.ing a rfllSBd-OII 1 benzothiazole,

benzothiazolium perchlorate,

where-Zrrepresents {the atoms,- necessary to complete an azole ring,preferably an azole ringahavarylene nucleus, e. g thiazole,,benzoxazole, :benzoselenazole, .naphthothiazole, etc., and nisyaninteger-from 5. 13010. ,The quaternary salt may; be awhloride,

.bromide, (iodide, nsulfate, ,petoluene :sulfonate, perchlorate etc.

The quaternary saltsxwhich.-l;.prefer to use have the .-formula:

-e. g. chloride, bromide, iodide, sulfate, para- "toluene. sulfonate,etc.

The following are suitable compounds: Pentamethylene bis abenzothiazolium perchlorate, heptamethylene-1bisidecamethyleneebisbenzothiazolium perchlorate. Other" bisquaternary salts of antifoggants may be used, c. .g. the bisquaternary-salts of the thiazoles, naph- "stitution such as alkyl,aryl,.alkoxy. or halogen *Thetoptical sensitizing dyes useful in mymixe'd grain emulsions embrace the "following:

( 1.) Carbocyanines derived from ,e-naphtho- "These include .carbocyaninechloride. 3,3 -'dimethyl 9 -;phenyl-- 4.5.4.25 :dibenzithiacarbocyanine bromide.

4,5,425" dibenzthiacarbocya nine bromide.

these grains if used on utes at 50 chlorate, in the amount 3dichloroselenacarbocyanine bromide (made by the method of White U. S.Patent 1,990,681, using 5-chloro-2-methylbenzoselenazole instead of 2-methylbenzoselenazole). These are red sensitizers.

(3.) 3, 3" bocyanines and oxacarbocyanines White U. S. Patent 2,478,366)

These include 3,3 dimethyl 8,10 m

anine bromide.

3,3 dimethyl 8,10 m

anine bromide.

- dimethyl 8,10 aryloxythiacar (Brooker and toloxythiacarbocytoloxyoxacarbocy 1 and 1' ,3-diethyl-4,5-benz-6-methylthia-2'-cyaninebromide (Brooker U. S. Patent 1,935,696). These are green sensitizers.

The optical sensitizing dyes are preferably used at a concentration offrom '7 to 50 mg. of sensitizing dye per liter of silver halide emulsioncontaining about 0.25 gram mole of silver halide per liter of emulsion.

According to my invention, the silver halide emulsion is treated withthe quaternary salt before or after optical sensitizing. In the case ofthe blue sensitive component of the mixture, no optical sensitizing dyeis ordinarily used. With the red-sensitive and green-sensitivecomponents of the mixture, the silver halide is optically sensitized tothe desired spectral region and is then treated with the quaternarysalt, although the quaternary salt may be omitted from the unsensitizedbluesensitive grains. The amount of quaternary salt may vary from about20 to 400 milligrams per mole of silver halide. To form the mixed grainemulsion, silver halide emulsions sensitized to different spectralregions are mixed in approximately equal amounts or in amountscontaining approximately equal quantities of silver.

, -The following example illustrates the forma tion of a mixed grainemulsion according to my invention:

To a blue-sensitive silver halide emulsion containing 98 mole-percentsilver bromide and 2 mole percent silver chloride there was addeddecamethylene-bis-benzothiazolium perchlorate in the proportion of 1'75mg. per mole of silver halide and the emulsion was digested with it for5 minutes at 50 C., then cooled to coating temperature of about 40 C.

A red-sensitive equal 'to 20 mole-percent of the silver and chloride inexcess of the remaining 80 mole-percent was sensitized with3,3-dimethyl-9-phenyl- 4,5,4,5'-dibenzthiacarbocyanine chloride, 88 mg.per mole of silver halide, and digested 5 min- C. with the dye. Aftercooling to 40 decamethylene-bis-benzolthiazolium peroi 175 mg. per moleof silver halide was added.

To a green-sensitive emulsion of the same emulsion containing bromide.

4 silver halide composition as the red-sensitive emulsion, there wasadded 3,3,9-triethyl-5,5'- diphenyl oxacarbocyanine bromide in theamount of 88 mg. per mole of silver halide, the emulsion was digested 5minutes at 50 C. and then cooled to C. anddecamethylene-bis-benzothiazolium perchlorate was added in the amount of1'75 mg. per mole of silver halide.

The usual spreading agents and hardener were added to each of theemulsions and. the emulsions were then mixed in amounts containing equalamounts of silver and immediately coated.

After drying, this coating was exposed to a color chart and processed asdescribed in Example-4 of U. S. Patent 2,592,243 of Carroll and Hanson.There' was no detectable diffusion of sensitizing dyes.

It will be understood that these examples are illustrative only and thatmodifications may be made in the method and material within the scope ofthe appended claims.

I claim:

1. A mixed grain photographic emulsion containing at least two sets ofsilver halide grains sensitive to difierent spectral regions, at leastone of said sets of grains being sensitized with a cyanine sensitizingdye and at least one of said sets of grains having adsorbed thereto aquaternary salt of the structure:

CH C104 C104 3. A mixed grain photographic emulsion containing sets ofsilver halide grains sensitive respectively to the blue, green and redspectral regions, at least one of said sets of grains bein sensitizedwith a cyanine sensitizing dye and at least said blue-sensitive grainshaving adsorbed thereto a quaternary salt of the structure:

C C104 C104 silver halide grains by diffused optical sensitizer in aBURT H. CARROLL.

References Cited in the file of this patent UNITED STATES PATENTS NameCarroll et a1.

Number Date June 30, 1942

1. A MIXED GRAIN PHOTOGRAPHIC EMULSION CONTAINING AT LEAST TWO SETS OFSILVER HALIDE GRAINS SENSITIVE TO DIFFERENT SPECTRAL REGIONS, AT LEASTONE OF SAID SETS OF GRAINS BEING SENSITIZED WITH A CYANINE SENSITIZINGDYE AND AT LEAST ONE OF SAID SETS OF GRAINS HAVING ADSORBED THERETO AQUATERNARY SALT OF THE STRUCTURE: